Ch 13 N+

local collision

A collision that occurs when two or more stations are transmitting simultaneously. Excessively high collision rates within the network can usually be traced to cable or routing problems.

late collision

A collision that takes place outside the normal window in which collisions are detected and redressed. Late collisions are usually caused by a defective station (such as a card, or transceiver) that is transmitting without first verifying line status or by failure to observe the configuration guidelines for cable length, which results in collisions being recognized too late.

jabber

A device that handles electrical signals improperly, usually affecting the rest of the network. A network analyzer will detect a jabber as a device that is always retransmitting, effectively bringing the network to a halt. A jabber usually results from a bad NIC. Occasionally, it can be caused by outside electrical interference.

cable tester

A device that tests cables for one or more of the following conditions: continuity, segment length, distance to a fault, attenuation along a cable, near-end cross talk, and termination resistance and impedance. Cable testers may also issue pass/fail ratings for wiring standards or store and print cable testing results.

voltage event recorder

A device that, when plugged into the same outlet that will be used by a network node, gathers data about the power that outlet will provide the node.

ohmmeter

A device used to measure resistance in an electrical circuit.

voltmeter

A device used to measure voltage (or electrical pressure) on an electrical circuit.

supported services list

A document that lists every service and software package supported within an organization, plus the names of first- and second-level support contacts for those services or software packages.

ghost

A frame that is not actually a data frame, but rather an aberration caused by a device misinterpreting stray voltage on the wire. Unlike true data frames, ghosts have no starting delimiter.

TDR (time domain reflectometer)

A high-end instrument for testing the qualities of a cable. It works by issuing a signal on a cable and measuring the way in which the signal bounces back (or reflects) to the TDR. Many performance testers rely on TDRs.

Network Monitor

A network monitoring program from Microsoft that comes with Windows Server 2003 and Server 2008 (as well as with Windows NT and Windows 2000 Server).

giant

A packet that exceeds the medium's maximum packet size. For example, any Ethernet packet that is larger than 1518 bytes is considered a giant. help desk analyst - A person who's proficient in basic (but not usually advanced) workstation and network troubleshooting. Help desk analysts are part of first-level support.

runt

A packet that is smaller than the medium's minimum packet size. For instance, any Ethernet packet that is smaller than 64 bytes is considered a runt.

OTDR (optical time domain reflectometer)

A performance testing device for use with fiberoptic networks. An OTDR works by issuing a light-based signal on a fiber-optic cable and measuring the way in which the signal bounces back (or reflects) to the OTDR. By measuring the length of time it takes the signal to return, an OTDR can determine the location of a fault.

help desk coordinator

A person who ensures that help desk analysts are divided into the correct teams, schedules shifts at the help desk, and maintains the infrastructure to enable analysts to better perform their jobs. They might also serve as third-level support personnel, taking responsibility for troubleshooting a problem when the second-level support analyst is unable to solve it.

change management system

A process or program that provides support personnel with a centralized means of documenting changes made to the network.

baseline

A record of how a network operates under normal conditions (including its performance, collision rate, utilization rate, and so on). Baselines are used for comparison when conditions change.

multimeter

A simple instrument that can measure multiple characteristics of an electric circuit, including its resistance and voltage.

tone locator

A small electronic device that emits a tone when it detects electrical activity on a wire pair. When used in conjunction with a tone generator, it can help locate the termination of a wire pair.

tone generator

A small electronic device that issues a signal on a wire pair. When used in conjunction with a tone locator, it can help locate the termination of a wire pair.

call tracking system

A software program used to document technical problems and how they were resolved (also known as help desk software).

network monitor

A software-based tool that monitors traffic on the network from a server or workstation attached to the network. Network monitors typically can interpret up to Layer 3 of the OSI model.

butt set

A tool for accessing and testing a telephone company's local loop. The butt set, also known as a telephone test set or lineman's handset, is essentially a telephone handset with attached wires that can be connected to local loop terminations at a demarc or switching facility.

spectrum analyzer

A tool that assesses the characteristics (for example, frequency, amplitude, and the effects of interference) of wireless signals.

cable performance tester

A troubleshooting tool that tests cables for continuity, but can also measure cross talk, attenuation, and impedance; identify the location of faults; and store or print cable testing results.

continuity tester

An instrument that tests whether voltage (or light, in the case of fiberoptic cable) issued at one end of a cable can be detected at the opposite end of the cable. A continuity tester can indicate whether the cable will successfully transmit a signal.

fox and hound

Another term for the combination of devices known as a tone generator and a tone locator. The tone locator is considered the hound because it follows the tone generator (the fox).

voltage event

Any condition in which voltage exceeds or drops below predefined levels.

third-level support

In network troubleshooting, a person or group with deep knowledge about specific networking topics to whom second-level support personnel escalate challenging problems.

second-level support

In network troubleshooting, a person or group with deeper knowledge about a subject and to whom first-level support personnel escalate problems.

first-level support

In network troubleshooting, the person or group who initially fields requests for help from users.

escalate

In network troubleshooting, to refer a problem to someone with deeper knowledge about the subject. For example, a first-level support person might escalate a router configuration issue to a second- or third-level support person.

optical time domain reflectometer

See OTDR.

time domain reflectometer

See TDR.

lineman's handset

See butt set.

telephone test set

See butt set.

cable checker

See continuity tester.

network analyzer

See protocol analyzer.

packet sniffer

See protocol analyzer.

sniffer

See protocol analyzer.

toner

See tone generator.

probe

See tone locator.

promiscuous mode

The feature of a network adapter that allows it to pick up all frames that pass over the network - not just those destined for the node served by the card. protocol analyzer - A software package or hardware-based tool that can capture and analyze data on a network. Protocol analyzers are more sophisticated than network monitoring tools, as they can typically interpret data up to Layer 7 of the OSI model.

negative frame sequence check

The result of the CRC (cyclic redundancy check) generated by the originating node not matching the checksum calculated from the data received. It usually indicates noise or transmission problems on the LAN interface or cabling. A high number of (nonmatching) CRCs usually results from excessive collisions or a station transmitting bad data.